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Article: What Is Thyroid Hormone And What Does It Do?

What Is Thyroid Hormone And What Does It Do?

What Is Thyroid Hormone And What Does It Do?

The thyroid gland, and thyroid hormone are misunderstood, and often taken for granted.

But *ahem* how's the job of being MASTER GLAND working out for you?

Yes, you read that correctly. The thyroid is considered the master gland, meaning it has control over several other glands, which in turn, release hormones and regulate metabolic processes..

By the end of this blog, you will have a new appreciation for the thyroid and its importance in our overall health.

Where Is The Thyroid Gland Found?

The thyroid gland is a small butterfly-shaped gland located at the front of the neck. It produces a hormone that regulate the body’s metabolic rate, energy levels, among other functions. These hormones affect almost every cell in the body and play an essential role in maintaining health.

What Hormones Does the Thyroid Produce?

The thyroid gland produces two hormones, namely triiodothyronine (T3) and thyroxine (T4). These hormones are essential for controlling our metabolism and regulating other hormones in our body.

t3 and t4

T3 is the active form of the thyroid hormone and is composed of 3 iodine atoms per molecule. T4 is the storage hormone, composed of 4 iodine atoms per molecule, and is converted to T3 in the body as needed. Together, these two hormones regulate our metabolism, growth, development and many other bodily functions.

The Importance Of Iodine In Thyroid Hormone Synthesis

Iodine is an essential component of the synthesis of thyroid hormones. Iodine atoms are taken up by the thyroid gland and incorporated into the organic molecules of the hormones thyroxine (T4) and triiodothyronine (T3).

The body needs enough iodine to produce thyroid hormones, and too little iodine can lead to a deficiency in hormones, resulting in hypothyroidism. To prevent this, it is important to get sufficient iodine through diet or supplementation.

Spirulina, found in Field of Greens, is a natural source of iodine to help support you getting the RDI.

It is noteworthy to mention that an excess of fluorine, such as that present in water, could impair iodine absorption by the body, thus possibly resulting in thyroid dysfunction.

Role Of Thyroid Hormone In Health

Regulating Metabolism

One of the main functions of thyroid hormone is to regulate metabolism. This hormone plays a key role in controlling how quickly, and efficiently the body converts food into energy and utilizes it.

It helps regulate the rate of energy production and consumption in the body, and helps maintain a healthy balance between the two under normal circumstances.

Maintaining Body Temperature

Thyroid hormone also helps to keep the body’s temperature at a consistent level. It increases the body’s metabolic rate and increases the production of heat. When the body’s temperature falls too low, the thyroid hormone stimulates the body to produce more heat to raise the temperature back to normal. When the body’s temperature rises too high, the thyroid hormone reduces the production of heat to lower the temperature back to normal.

body temperature check

Simply put, thyroid hormone helps to regulate body temperature by increasing heat production when it is cold and decreasing when it is hot. Its just one of the ways that the amazing human body is able to function properly in wildly diverse climatic conditions.

Regulating Heart Rate

There is a tightly controlled balancing act that leads to regulating heart rate. Thyroid hormone actually plays a critical role in this function. The hormone helps regulate the heart rate by signaling for an increase in the number of contractions of the heart, which results in faster beats per minute.

It can also increase the amount of blood that is pumped out of the heart with each contraction, which will also lead to a reflex increase in heart rate.

Finally, the hormone can also cause an increase in the amount of oxygen delivered to the heart, which ,again, can lead to an increase in heart rate.

Supporting Cognitive Function

Thyroid hormone also has a role in supporting cognitive functions. It helps with the development of the brain and the formation of memories, as well as controlling the release of neurotransmitters that regulate cognitive functions.

A Deficiency in thyroid hormone can lead to issues with concentration, memory, and mood. It is important to make sure that the thyroid is functioning properly in the event that other investigations fail to yield a diagnosis for a cognitive issue.

Keeping Bones Healthy

One of the key functions of thyroid hormone is to help keep bones healthy. This hormone stimulates the body to absorb calcium and phosphorus, which are essential minerals for strong bones.

It also encourages the production of osteoblasts, which are cells that help form new bone tissue. Low thyroid hormone levels can cause an imbalance in calcium and phosphorus blood levels, leading to weakened and brittle bones from poor absorption and mineralization.


Did you know that the thyroid also helps improve immunity? It does this by increasing the production of white blood cells, which are responsible for defending the body against foreign invaders such as bacteria, viruses, and toxins.

white blood cells

Additionally, thyroid hormone helps the body produce antibodies, which can help it recognize and destroy foreign invaders more efficiently. This helps to maintain a strong and healthy immune response, which is essential for fighting off illnesses and infections.

Maintaining Circadian Rhythm

In addition to its many stimulatory type actions, it also plays a regulatory roll in your circadian rhythm. This is the body’s internal clock that regulates sleep-wake cycles and other daily cycles such as body temperature, hormone production, and metabolism.

It is controlled by a cluster of cells located in the brain called the suprachiasmatic nucleus. Thyroid hormone assists with modulating the circadian rhythm by affecting the production of melatonin, a hormone that helps to regulate sleep-wake cycles.

Melatonin is produced in the pineal gland and is responsible for helping us fall asleep and stay asleep. Without proper levels of thyroid hormone, melatonin production can be interrupted, leading to sleep disturbances.

If you suspect you are suffering from melatonin impairment, using a supplement with that ingredient can help restore your sleep cycle.

Cardiovascular Health

Did you ever wonder how the thyroid can contribute to heart health? Thyroid hormones help to regulate the levels of triglycerides, cholesterol, and lipoproteins in the bloodstream.

These substances all play an important role in cardiovascular health. When they are out of balance it can lead to fatty deposits forming on artery walls, which can eventually lead to heart disease and stroke.

Thyroid hormone helps to keep these substances at optimal levels by supporting their metabolism, which is important for overall cardiovascular health.


An iodine deficiency is strongly associated with stunted growth and developmental delays. This is directly as a result of impaired thyroid synthesis. Thyroid hormone plays an important role in growth as it helps to regulate the production of proteins, which are essential for cell growth and tissue repair.

It also supports bone development and muscle function, both of which contribute to physical growth. In fact, low levels of thyroid hormone can lead to a slowed metabolism and increased weight gain, which can further inhibit growth in children.

On the other hand, hyperthyroidism can cause a child to grow more quickly than their peers.

Coupled with the fact that thyroid hormone also regulates the release of other growth promoting hormones, you can see why it is so important.

Mitochondrial Function

Mitochondria are the powerhouse of cells, responsible for the production of energy. Thyroid hormones play a major role in the maintenance of mitochondrial function. They increase the mitochondria’s ability to use oxygen, as well as their ability to metabolize fat and carbohydrates. In turn, this can ensure that the mitochondria are producing energy at a steady rate.

Thyroid hormone also has a protective effect on the mitochondria, safeguarding them from oxidative damage.

Disorders of The Thyroid

Thyroid conditions are a common but often misunderstood medical issue. Hypothyroidism and hyperthyroidism are the two most common conditions and are caused by an imbalance in the production of hormones. While they have some similarities, there are also distinct differences between the two that it is important to recognize.

hypo and hyperthyroidism

Symptoms of Hypothyroidism

Hypothyroidism is a condition in which the thyroid gland does not produce enough of the hormones necessary for healthy functioning. Common symptoms of hypothyroidism include fatigue, weight gain, dry skin and hair, depression, constipation, memory issues, and feeling cold more often than usual.

It is important to note that not all of these symptoms may be present in every case of hypothyroidism - some people may only experience one or two of these symptoms.

Symptoms of Hyperthyroidism

Hyperthyroidism, on the other hand, occurs when your thyroid produces too much of the hormone thyroxine. This can cause symptoms such as weight loss, rapid heartbeat, nervousness, irritability, and profuse sweating.

It can also cause development of a goiter, an enlargement of the thyroid gland in the neck. Other symptoms can include hair loss, heat intolerance, insomnia, and vision changes.

Causes of Hypothyroidism

Hypothyroidism occurs when the thyroid gland does not produce enough of the thyroid hormones, which are responsible for regulating metabolism. The main causes of hypothyroidism are autoimmune diseases, medical treatments, and iodine deficiency.

Autoimmune diseases, such as Hashimoto’s thyroiditis and Graves’ disease, cause the body's immune system to attack the thyroid gland and prevent it from producing enough thyroid hormones.

Medical treatment, such as radiation therapy, can also damage the thyroid gland and cause hypothyroidism.

Causes of Hyperthyroidism

The primary cause of hyperthyroidism is also the autoimmune disorder called Graves’ disease, which causes the body to produce antibodies that attack the thyroid. Other causes of hyperthyroidism include nodules on the thyroid that produce too much of the hormone, benign or malignant tumors, thyroiditis (inflammation of the thyroid), and the overuse of thyroid medications.

People who have other autoimmune conditions, such as type 1 diabetes, celiac disease, and Addison’s disease, are also more prone to developing hyperthyroidism.

Other Contributing Factors

Nutritional deficiencies: Certain nutrients, such as iodine, selenium, and tyrosine are essential for the production of thyroid hormones. A lack of these nutrients can lead to an imbalance in the levels of these hormones, and usually cause hypothyroidism.

Medication Side Effects

Many medications can affect the thyroid hormones, including some used to treat depression, heartburn, and high blood pressure.


Stress is an important contributing factor to many health problems, including thyroid hormone imbalance.

Hormonal Imbalances

Other hormones, such as estrogen and progesterone, can affect the production of thyroid hormones.

Environmental Toxins

Exposure to chemicals such as bromine, chlorine, fluoride and heavy metals can interfere with the production of thyroid hormones.

Treatments Approaches

Treatments for both hypothyroidism and hyperthyroidism can vary depending on the severity and underlying cause of the disorder.

For hypothyroidism, the most common form of treatment is hormone replacement therapy. This involves taking a daily dose of synthetic thyroid hormone, usually levothyroxine, to make up for what your body is not producing.

In some cases, doctors may also recommend taking selenium or iodine supplements to help regulate the hormone production naturally.

For hyperthyroidism, the most common forms of treatment are antithyroid drugs, radioactive iodine, or surgical removal of the thyroid gland.

Antithyroid drugs are used to reduce the overactive production in the thyroid, while radioactive iodine is used to damage or destroy a part/ entirety of the gland so that it produces less of the hormone.

Surgery is a more extreme option, but it is an effective way to permanently remove the source of the hormone dysfunction.

Thyroid Hormone Testing

Testing for thyroid hormone levels is an important part of determining the health of the thyroid gland. Most commonly, this is done through a blood test, where the levels of thyroxine (T4) and triiodothyronine (T3) are measured.

thyroid blood testing

In some cases, additional tests may be needed to assess the levels of thyroid stimulating hormone (TSH) and other hormones produced by the thyroid gland. These tests help to diagnose an underactive or overactive thyroid, and to assist with the management options if either are detected.

Final Words

If you find that you're having an extrenely difficult time losing weight, or even retaining lean muscle mass, there's a chance that thyroid dysfunction could be the culprit. Consult with your doctor to get a comprehensive thyroid hormone test done, and if necessary, discuss potential treatment options.

If treated properly, thyroid disorders can often be managed through lifestyle modifications and medication/supplementation, leading to improved overall health and wellbeing.

The thyroid is just so important- don't take the little signs for granted!


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